After four years of denial, the Iraqi government, desperate for the lifting of international sanctions against it, has finally admitted that it developed a powerful, offensive biological weapons program in the years leading to the Gulf war, U.N. officials reported Wednesday.

But Iraq asserted that it had destroyed all the biological weapons a few months before allied planes began bombing Iraq in January 1991.

U.N. officials said they would soon try to verify this.

The officials described the admission as a first step in Iraq’s attempt to complete its compliance with U.N. resolutions demanding that it account for and destroy all its weapons of mass destruction.

Until Iraq complies, according to the resolutions, a total embargo on Iraqi oil exports remains in place.

The U.N. Special Commission, which is overseeing the disbanding of these programs, declared itself satisfied last month that Iraq is rid of its nuclear weapons, chemical weapons and long-range missile programs.

The big question mark has long centered on biological weapons because of the commission’s refusal to believe Iraq’s persistent denials that it ever had such a program.

Iraq’s admission did not mean that the commission would be able to verify the assertion quickly.

U.S. Ambassador Madeleine K. Albright, noting that it had taken the Special Commission almost four years to satisfy itself that the Iraqi nuclear weapons program was eliminated, said that Baghdad’s cooperation would now determine “whether it’s going to take four months or four years” to verify Iraq’s claims.

In other action, the Security Council, by a vote of 14-0 with Russia abstaining, passed a resolution continuing the suspension of several light sanctions on Serbia.